Re: [PATCH v10 08/12] iommu/sva: Refactoring iommu_sva_bind/unbind_device()

[Baolu Lu]

On 2022/7/25 15:50, Tian, Kevin wrote:
> > From: Baolu Lu <baolu.lu@xxxxxxxxxxxxxxx>
> > Sent: Sunday, July 24, 2022 9:48 PM
> > > The API is really refcounting the PASID:
> > >
> > > > +struct iommu_sva *iommu_sva_bind_device(struct device *dev,
> > > > +					struct mm_struct *mm);
> > > > +void iommu_sva_unbind_device(struct iommu_sva *handle);
> > >
> > > So what you need to do is store that 'iommu_sva' in the group's PASID
> > > xarray.
> > >
> > > The bind logic would be
> > >
> > >     sva = xa_load(group->pasid, mm->pasid)
> > >     if (sva)
> > >        refcount_inc(sva->users)
> > >        return sva
> > >     sva = kalloc
> > >     sva->domain = domain
> > >     xa_store(group->pasid, sva);
> >
> > Thanks for the suggestion. It makes a lot of sense to me.
> >
> > Furthermore, I'd like to separate the generic data from the caller-
> > specific things because the group->pasid_array should also be able to
> > serve other usages. Hence, the attach/detach_device_pasid interfaces
> > might be changed like below:
> >
> > /* Collection of per-pasid IOMMU data */
> > struct group_pasid {
> > 	struct iommu_domain *domain;
> > 	void *priv;
> > };
>
> Is there any reason why pasid refcnt is sva specific and needs to be
> in a priv field?

I am going to store the iommu_sva data which represents the bind
relationship between device and domain.

Best regards,
baolu